Plastic molding machines



Om. 4, 1955 R. H. DYKEHOUSE 2,719,326

PLASTIC MOLDING MACHINES Filed Feb. 28, 1950 4 Sheets-Sheet 1 Oct.. 4,1955 R. H. DYKEHOUSE 2,719,326

PLASTIC MOLDING MACHINES Filed Feb. 28, 1950 4 Sheets-Sheet 2 y ALM Oct.4, 1955 R. H. DYKEHOUSE 2,719,326

PLASTIC MOLDING MACHINES Filed Feb. 28, 1950 4 Sheets-Sheet I5 5.3 ff f4/5/ Oct. 4, 1955 R. H. DYKEHOUSE 2,719,326

PLASTIC MOLDING MACHINES Filed Feb. 28, 1950 4 Sheets-Sheet 4 UniteStates Patent PLASTIC MULDlNG MACHINES Robert H. Dykehonse, Los Angeles,Calif., assigner to Crown Machine and Tool Company, inc., Fort Worth,Tex., a corporation of Texas Application February 28, 1950, Serial No.14ti,S'/`9 3 Claims. (Cl. 1.8-30) This invention relates to improvementsin plastic molding machines, and has for one purpose to provide animproved pre-plasticizing unit.

Another purpose is to provide a pre-plasticizing chamber assembly inwhich plasticizable solids may be quickly and efficiently plasticizedunder relatively low pressures.

Another purpose is to provide an improved association between apre-plasticizing unit and an injector unit, whereby preplasticizedmaterial may more eciently be fed into the mold.

.Another purpose is to provide improved means for heating thepre-plasticizing chamber.

Another purpose is to provide a pre-plasticizing unit which iseitlciently and easily assembled and disassembled in molding machines.

Another purpose is to provide such a unit with readily removable andinsertable heating elements.

Another purpose is to provide an improved valving assembly for apre-plasticizing unit and its associated injection unit.

Other purposes will appear from time to time in the course of thespecication and claims.

rlhe invention is illustrated more or less diagrammati" cally in theaccompanying drawings wherein:

Figure l is a vertical section, with parts in side elevation;

Figure 2 is a section, on an enlarged scale, on the line 2 2 of Figurel;

Figure 3 is a bottom View of one element of the preinjection unit shownin Figure l;

Figure 4 is a section on the line iw-4 of Figure 3;

Figure 5 is a top view of another element or the unit;

Figure 6 is a section on the line 6 6 of Figure 5;

Figure 7 is a bottom view of the element shown in Figure 6;

Figure 8 is a top plan view of the lower member ot the pre-injectionunit;

Figure 9 is a section on the line 9-9 of Figure 8;

Figure l0 is a vertical section through another form of t-he device;

Figure ll is a side elevation of the structure shown in Figure l0; and

Figure l2 is a diagrammatic illustration of a method of Welding the unitof Figures l0 and ll.

Like parts are indicated by like symbols throughout the specificationand drawings.

Referring to the drawings, l generally indicates the injection cylinderot a plastic molding machine. lt is shown as enclosed in any suitablesupport or block il.. 3 is a nozzle portion shown as having an initiallytapered bore Il, a further and somewhat more gradually tapered bore 5,and a discharge bore 6 leading to and communieating with any suitabledischarge nozzle 7. The nozzle 7 is shown as an insert in the end oftheblock 3.

The actual outflow of plasticized material is controlled by any suitablevalve 8 which may, for example, be of an axially sliding type, although,of course, any suitable type of valve may be employed. 9 indicates anysuitable piston, shown as mounted on a piston rod 10, passing throughany suitable stufng box or the like, indicated at lll. It will beunderstood that any suitable means, not herein shown, may be employedfor moving the piston 9 toward and away from the nozzle end of thecylinder 1.

2l) indicates any suitable Storage or teed hopper in which plasticmaterials, including thermoplastics, may be stored or fed. Suchmaterials may be furnished in separate particles of granular or othersize.

In the use of my preplasticizing unit the plastic materials, initiallysuitably divided, are fed downwardly through the hopper 20, through theneck 21, and into the hopper-shaped surface 23 of the hopper base orsupport 22. Any suitable means, not herein shown in detail, may beemployed for feeding or agitating the plasticizable solids. lt will beunderstood that the solids are pre-plasticized in the course of theirmovement beyond the hopper-like surface 23 to the cylinder l. Forexample, fl illustrate a unit including a bottom plate 25 which may besecured to or form part of the member 2. A top plate 26 is secured to itby any suitable screws or other connections 27. Between the two, lillustrate a pre-plasticizing unit having the elements generallyndicated as A, B and C, which `will later be described in detail.

Above the top plate l illustrate an insulating member or shell 2i;within which is a layer or body of insulating material 29. The hopperbase 22 is shown as rmly secured in relation to the top plate 26 byscrews 29a which may extend through the shell 28 and insulation 229, andwhich hold the parts firmly together. lt will be noted that theinsulating layer 29 is received within a recess Zilla in the shell 28. Afurther recess may form a passage Ell for any suitable coolant, thepassage being completed by the hanged ring 3l.

The .ring 3l and 'the insulation 29 surround the tubular passage 32.This passage element is shown as outwardly flanged as at 33. lts innerbore constitutes a passage for the reception of the plasticizablesolids. Its cylindrical interior is formed and adapted to receive areciprocating feed piston 34 guided in any suitable guide or guides 35,and provided with any suitable limit stop or enlargement 3d. The detailsof the mechanism for reciprocating the piston 3d need not be shown, butit will be understood that any suitable means may he employed forreciprocating the piston 3d into and out of the bore of the tube orcylinder whereby plasticizable solids fed by or through the hopper Ztlmay be positively fed or forced downwardly through the cylinder 32 andinto the pre-plasticiziug unit below described.

Referring to the preplasticizing unit proper, its upper member is shownin Figures 3 and 4, its intermediate member E is shown in Figures 5, 6and 7, and its lower member C is shown in Figures 8 and 9. lt isadvantageous to arrange the unit in a series of interpenetratingelements, as shown, which can easily be assembled together and heldfirmly in position. The upper member A of Figures 3 and 4 is formed.with a central bore 40 l1 dg an upper enlargement All to receive thedownwardly extending end of the sleeve El?. which extends into a bottomenlargement d2, Shown as having a rounded outer vlace d3. The member Ais shown as provided with a. plurality of bolt holes dftand also withradial bores adapted to receive outwardly removable heating units lll-6,the t etails of which do not of themselves form part of the presentinvention. Apertures 47 are also provided, as shown, `for example, inFigure l, to receive any suitable thermally responsive elements 48,whereby automatic temperature control may be provided.

The intermediate member, generally indicated as B, and shown in sectionin Figure 6, has an outer thickened portion 50 having upper and -lowerconic surfaces 51 and 52 to receive appropriately formed parts of themembers A and C when the parts are nested as shown in Figure l. An-inner`enlargement 53 has its upper surface formed wit-h yan outer roundedportion 54, an intermediate and generally llat portion 55, and agenerally conic central projection' 56.

Vlt will be observed that the opposed faces of elements A and B contactat 51 but are spaced apart to deiine between them an outwardlyexpandingA passage in communication with the passage or bore 40. Thispassage extends entirely around the rounded portion 54, being thus openfrom edge to edge, with no interruption or interference to the outwardpassage of the plastic material delivered downwardly through the sleeve32 and the bore 40. l-lowever, the outer portion 50 and the innerportion 53 of the member B are separated by what may be called a trenchor depression 57 in the bottom of which are illustrated a plurality ofapertures 58 through which, as will later appear, the alreadyYplasticized material may ow.

The bottom member C has a conic surface 6% adapted to receive the lowerconic surface 52 of the member B. Thus the intermediate parts of the twomembers are spaced apart, as shown in Figure 1. The lower surface 61 ofthe member B is spaced somewhat away from the upper surface 62 of theintermediate part of the member C. 63 indicates a tapered passage which,with the conic downward projection 64 of the member B, defines arelatively restricted discharge passage which communicates with afurther restricted down passage 63a and a passage portion 65, even morerestricted than 63a. The actual outlet passage 65 is controlled by anysuitable valve 66 which, for example, may be of the rotary or thesliding type. The lower surface of the member C may be generally plane,as at 70, with a central projection 71 entering an appropriate apertureor seat 72 in the base plate 25.

It will be observed that the members A, B and C are rmly connected by aplurality of screws 75 passing through apertures 44 in the member A, andappropriately aligned apertures 44b and 44e in the other two elements.Thus the pre-plasticizing element as a unit may be assembled ordisassembled and secured as a unit to the base plate 25, where it isheld in position by the screws 27. The hopper unit is shown as securedto the top plate 26, but I find it preferable also to provide aplurality of screws 29a which actually enter threaded apertures 29h inthe upper surface of the element A. lt will be noted that each of theelements A, B and C is provided with a plurality of the apertures 45into which resistance elements or heating units 46 may be inserted. Itis preferable to arrange them radially for easy insertion and removaland for relatively uniform heating effect. It will be noted that theapertures 4S of the unit B pass through bridges between adjacentdischarge apertures of passages 57.

It is also advantageous to provide heat responsive members 4S insuitable apertures 47. For example, in Figure 1, one such thermocoupleor heat responsive unit is illustrated positioned in the member A at apoint just above the surface 42. A similar unit is shown in Figure l inthe member C just below the surface 62. Any suitable indicating andcontrol means, automatic or otherwise, may be employed, for advising theoperator as to temperature conditions in the pre-plasticizing unit andfor automatically controlling the heating conditions. For example, it ispractical to control the current flowing through the leads 100 of thevarious heating units 46 to maintain the desired temperature and thedesired temperature relationship between dilferent parts of the unit.

Whereas valves 8 and 66 have been indicated, one eective to control theflow of plasticized material from the pre-plasticizing unit, and theother to control the liow of plasticized material from the 'maincylinder 1, the -specic operating connection or relationship between theValves is not indicated. It is thought not necessary, since the twovalves may be connected by a wide variety of different methods. What isimportant is that when the valve 66 is open, to permit the ow ofpre-plasticized material into the interior of the cylinder 1, the valve8 is closed. On the other hand, when the piston 9 advances, the valve 66is closed and the valve 8 is open to permit the flow of the plasticizedmaterial through the discharge tip 7 into any suitable mold.

As an example of the foregoing, a fluid motor may be employed to movethe piston 9. The Huid motor may be controlled by a valve having amovable member representative of the piston movement. In one position ofthe valve member the piston 9 is advancing and in another position thepiston is retracting. A solenoid may be employed to open and close valve8 and a solenoid may be employed to open and close valve 66. Eachsolenoid may be energized by a control circuit established by movementof the fluid motor valve member. llt/hen the piston 9 advances, thevalve member occupies one position to establish the circuit energizingthe solenoid to open Valve 8. When the piston 9 retracts, the valvemember occupies another position to establish the circuit energizing thesolenoid to open valve 66. Deeuergization of either solenoid results inclosing its associated valve.

ln pre-plasticizing units of the type herein shown, the interior of theunit may be subjected to exceedingly high pressures. Even though, in theform of Figures 1 and following, large numbers of the locking screws areemployed, under some circumstances it is advantageous to substitute,instead, a normally permanent connection between the individual parts.Referring to the structure ot Figures l0 and 1l, three elements, D, Eand F, bear substantially the same relationship to each other as theelements A, B and C of Figure l. They may be formed to define anysuitable form of pre-plasticizing passage, as shown, the individualparts being given the same indicating numerals as in Figures 1 andfollowing. Similarly, the individual elements are provided withapertures 45 and 47 to receive heating units 46 and thermally responsiveelements 48, as shown in Figures 1 and following. But the elements D, Eand F, instead of being connected by the bolts or screws 75, areactually welded to each other circumferentially, as at 101, 102.

ln forming the unit of Figures 10 and 1l it is advantageous initially toraise the individual elements D, E and F to a temperature of the orderof 800 F. They may then advantageously be subjected, when assembled andheated, to a pressure of the order of 400 tons. This provides adequatesealing for the high pressures to which the interior of the unit willlater be subjected. The unit is then welded circumferentially along thelines 101, 102, and may thereafter be nished to a smooth outer surface.

As shown in Figure l2, it is advantageous to employ four-point welding.

The unit of the type above described, factory-completed, factory-sealedand factory-tested, may then be stored or shipped for use in a widevariety of molding machines.

Whereas a practical and operative device has been described andillustrated, nevertheless many changes may be made in size, shape,number and disposition of parts without departing from the spirit of theinvention. It is intended that the description and drawings be taken asin a broad sense illustrative or diagrammatic, rather than as alimitation upon the invention.

The use and operation of the invention are as follows:

The pre-plasticizing unit herein shown is leak-proof and is ofsuiiicient strength for higher ram pressures, where such pressures arenecessary. The pre-plasticizing unit includes metal members A, B and Cwhich abut, and which, between themselves, define the necessaryexpanding passage through which the material undergoing plasticizingllows. As will be clear, for example, from Figure l, thepre-plasticizing unit, comprising the three elements A, B and C, isfirmlysecured together by screws '75. lt, in turn, is firmly grippedbetween the plates 25 and 26, being held by the external clamping screws27. Except for the annular heating element X, all of the heatingelements are insertable and removable radially, being received by thegenerally radial passages 45. The cartridge type heaters thus employedare spaced like the spokes in a wheel. It is unnecessary to tear downthe unit to replace burned out heaters, since the external heaters canbe replaced while the device is in operation.

The shut-olf valve 66 between the plasticizing chamber and the injectioncylinder effects an important im* provement in eiciency, and actuallyincreases the capacity of the injection cylinder. Without it, theplunger or piston 9 must be pre-set to cover at least one-half of theopening of the orice or outlet 65, to prevent the forward movement ofthe plunger 9 from forcing plastic material back into the plasticizingchamber instead of forwardly through the nozzle 7 into the mold. Theshutoff valve 66 operates in conjunction with and in timed relation withthe nozzle shut-olf valve 8. When the valve 8 opens, the valve 66closes. The valve action is reversed when the injection plunger orpiston 9 starts its return stroke.

In the form of Figures 10 and 11 a factory-assembled unit isillustrated, which is pre-sealed and pre-tested, and which may besupplied as a unit for use in a variety of plastic injection devices.For example, only the parts shown in Figure 10 need be supplied. Theuser normally has no access whatsoever to the interior of the device,and can and should do nothing to break the weld between the adjacentelements D, E and F. The unit thus supplied may then be built intomachines of dilferent sizes and capacities, the manufacturer preferablysupplying the resistance units, the thermocouples, and the valve, etc.

Where the unit is to be subjected to less than the extremely highpressures, the unit of Figure 1 may be employed, and may be sealed toprevent subsequent tampering. For example, as shown in Figure 1, a sealor weld may be superposed above the head of each of the screws 75, toprevent any tampering by the user, where the unit is to befactory-tested at its point of manufacture, and to be serviced only bythe manufacturer.

It will be understood that the unit is formed to receive any suitableupper and lower plates or bases, such as are shown at 2 and 26 inFigure 1. But the details of these plates and bases may be widely variedto suit the particular machine with which the unit is employed. The unitis properly designed to provide a feed passage or receiving passage intowhich the solid granules are fed. They are then subjected to any desiredpressure, as by the piston 34 or its equivalent.

The feed passage 32 of Figure l, when employed with the unit of Figure10, directs the material downwardly into the unit against the spreadersurface 55 which defines, with the opposed surface 42, a rapidlyexpanding mensions, and in passage thickness, to the bulk of thematerial to be fed and to the rate of feed, and to the passage portionwhich is related, in area, in radial dipressures and temperatures towhich the material is to be subjected.

In both forms of the device, zone control is employed, a plurality ofthermocouples being indicated as at 48, appropriately spaced todetermine and control the ternperature at the various zones throughwhich the material undergoing plasticization passes.

I claim:

1. A plasticizing unit adapted to be unitarily inserted and removed froma plasticizing assembly, including a housing formed of three sections,an inner and two outer sections, connected longitudinally and havingopen areas therein defining a plasticizing passage, the two outersections each having a generally central passage constituting an inletand outlet for the plasticizing passage and an inwardly facing dishedout portion, the center section including an outer annular member and aninner spreader member separated from the outer member by an annularchannel divided into a plurality of arcuate openings by a plurality ofislands, the inner spreader member extending at each end longitudinallybeyond the annular channel and defining right angle channels with thedished out portions in the outer sections, and three groups of laterallydisposed apertures for the reception of heating elements extending intothe sections, one group for each section, the apertures in each grouplying generally in a common plane generally parallel to the planes ofthe other groups and generally equally spaced with respect to each otherand also with respect to the right angle channels, the point ofconvergence of each group of apertures lying generally on the centerline of the inlet and outlet, each aperture in the group in the innersection passing through an island.

2. The structure of claim 1 in which the sections are welded together.

3. The structure of claim 1 in which the sections are bolted together.

References Cited in the le of this patent UNITED STATES PATENTS 33,055Smith et al Aug. 13, 1861 726,026 Canda Apr. 21, 1903 791,649 RichardsJune 6, 1905 1,624,501 Nelson Apr. 12, 1927 2,202,140 Birroughs May 28,1940 2,206,098 Lester July 2, 1940 2,207,426 Bailey July 9, 19402,359,840 Goessling Oct. 10, 1944 2,367,144 Shaver Ian. 9, 19452,428,315 Lester Sept. 30, 1947 2,465,889 Lester et al Mar. 29, 19492,480,313 Alden Aug. 30, 1949 2,491,343 Valyi Dec. 13, 1949 2,493,805Dinzl Jau. 10, 1950 2,501,595 Bohannon Mar. 21, 1950 2,582,260 KutikJan. 15, 1952 FOREIGN PATENTS 687,987 Germany Feb. 9, 1940

1. A PLASTICIZING UNIT ADAPTED TO BE UNITARILY INSERTED AND REMOVED FROMA PLASTICIZING ASSEMBLY, INCLUDING A HOUSING FORMED OF THREE SECTIONS,AN INNER AND TWO OUTER SECTIONS, CONNECTED LONGITUDINALLY AND HAVINGOPEN AREAS THEREIN DEFINING A PLASTICIZING PASSAGE, THE TWO OUTERSECTIONS EACH HAVING A GENERALLY CENTRAL PASSAGE CONSTITUTING AN INLETAND OUTLET FOR THE PLASTICIZING PASSAGE AND AN INWARDLY FACING DISHEDOUT PORTION, THE CENTER SECTION INCLUDING AN OUTER ANNULAR MEMBER AND ANINNER SPREADER MEMBER SEPARATED FROM THE OUTER MEMBER BY AN ANNULARCHANNEL DIVIDED INTO A PLURALITY OF ARCUATE OPENINGS BY A PLURALITY OFISLANDS, THE INNER SPREADER MEMBER EXTENDING AT EACH END LONGITUDINALLYBEYOND THE ANNULAR CHANNEL AND DEFINING RIGHT ANGLE CHANNELS WITH THEDISHES OUT PORTIONS IN THE OUTER SECTIONS, AND THREE GROUPS OF LATERALLYDISPOSED APERTURES FOR THE RECEPTION OF HEATING ELEMENTS EXTENDING INTOTHE SECTION, ONE GROUP FOR EACH SECTION, THE APERTURE IN EACH GROUPLYING GENERALLY IN A COMMON PLANE GENERALLY PARALLEL TO THE PLANE OF THEOTHER GROUPS AND GENERALLY EQUALLY SPACED WITH RESPECT TO EACH OTHER ANDALSO WITH RESPECT TO THE RIGHT ANGLE CHANNELS, THE POINT OF CONVERGENCEOF EACH EACH GROUP OF APERTURES LYING GENERALLY ON THE CENTER LINE OFTHE INLET AND OUTLET, EACH APERTURE IN THE GROUP IN THE INNER SECTIONPASSING THROUGH AN ISLAND.